In der vorliegenden Arbeit wird die Thermodiffusion von Oe02 in U02 untersucht. Es wird eine Anlage beschrieben, in der zylindrische Proben in einem Te=peraturgradienten zwischen 1400 und 2200°0 geglüht werden können. Die Oe02-Konzentration in den verwendeten Proben betrug 3.7, 5.6 und 13. Investigations of thermal diffusion of Oe02 in U02 are reported. An equipment is described in which cylindrical sampIes can be annealed in a temperature gradient between 1400°0 and 2200°O. The Oe02-concentrations in the used sampIes were 3.7, 5.6 and 13.3 wt %. The distribution ofOe02 after the annealing procedure in a temperature gradient was analysed by =eans of an electron microprobe unit. As the =ost important result it was established that the Oe02 migrates to the higher temperature by a thermal diffusion process. Thus, the Oe02-concentration decreases in the lower temperature range and increases in the higher temperature range. After annealing some days a minimum of Oe02-concentration at a temperature of 1700°0 and a maxiInum
The industrial sector is faced with ever increasing problems relating to the disposal of waste materials. At the same time, there are long term needs for increased energy supply which must generally be produced from cost intensive fossil fuels.The circulating fluid bed (CFB) is a highly efficient fluidized bed reactor wherein gaslsolid reactions can proceed with a minimum of mass transfer resistances [I]. It had been widely applied by Lurgi in the calcination of alumina and other materials [2, 31. When coupled with well designed components for the production of steam, this technology is now also being applied to produce energy from the combustion of coal as well as from various waste materials of high sulfur content or low heating value [4-61.Sulfur dioxide emissions are well controlled within the CFB system by direct injection of limestone, and NO, emissions are minimized by using a "staged combustion" configuration in the fluid bed. Many waste materials can thus he burned in an environmentally acceptable manner.Applications are also underway to utilize CFB systems for chemically treating potentially hazardous waste materials to produce desirable recycle products or harmless residues.
Tailor-making alumina characteristics as necessitated by the changing global structure of the aluminum industry can be accomplished by precise control of the calcining process.
SUMMARYThe two most frequently used types of alumina are finegrained, high-calcined, "floury" alumina and coarse-grained, low-calcined, "sandy" alumina; they
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